Condenser liquid delivery regulator for a refrigerated dryer having condensate harvester

ABSTRACT

An air compressor system useful for supplying a stream of compressed air for an end user is disclosed which includes a refrigerated dryer useful to remove moisture and harvest it from the compressed air. The refrigerated dryer includes an evaporator and a condenser, where the evaporator is useful to produce the moisture from the compressed air. The air compressor system includes an expansion tank which collects the harvested moisture from the evaporator. The expansion tank can provide liquid to a pump that conveys the liquid to a condenser of the dryer. The refrigerated dryer includes a temperature sensor that detects a temperature of refrigerated fluid associated with the condenser and regulates the pump to supply liquid to the condenser to assist in heat rejection.

TECHNICAL FIELD

The present invention generally relates to air compressor systems havinga refrigerated dryer, and more particularly, but not exclusively, toharvesting condensate from a compressed air stream of the air compressorsystem using the refrigerated dryer.

BACKGROUND

Providing condensate harvesting for air compressor systems remains anarea of interest. Some existing systems have various shortcomingsrelative to certain applications. Accordingly, there remains a need forfurther contributions in this area of technology.

SUMMARY

One embodiment of the present invention is a unique condensate harvesterused with a refrigerated dryer for a compressor system. Otherembodiments include apparatuses, systems, devices, hardware, methods,and combinations for harvesting condensate. Further embodiments, forms,features, aspects, benefits, and advantages of the present applicationshall become apparent from the description and figures providedherewith.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts an embodiment of a compressor system that includes adryer and condensate harvester.

FIG. 2 depicts another embodiment of a compressor system that includes adryer and condensate harvester.

FIG. 3 depicts another embodiment of a compressor system that includes adryer and condensate harvester.

FIG. 4 depicts another embodiment of a compressor system that includes adryer and condensate harvester.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

With reference to FIG. 1, an embodiment is illustrated of a compressorsystem 100 that includes a gas compressor 102 capable of producing acompressed gas stream 104 and a refrigerated dryer 106 useful forremoving water vapor from the compressed gas stream 104 prior toproviding the dried gas stream to an end user/facility compressed airsystem/etc.

The gas compressor 102 can take many forms including a positivedisplacement compressor, rotary compressor, etc. Any variety of gascompressors 102 are contemplated herein, such as rotary screwcompressors, centrifugal compressors, etc. The compressor 102 is capableof compressing any variety of fluids, with air being just onenonlimiting example. In one form the air that is compressed bycompressor 102 includes water vapor, such as might be expected to occurin elevated humidity locations.

The compressor system 100 can include an air to air heat exchanger 108used to exchange air between an uncooled compressed air stream from thecompressor 102, and the compressed air stream from the compressor 102after it has been cooled by the refrigerated dryer 106. Not allembodiments need include the air to air heat exchanger 108. In thoseembodiments, compressed air from the compressor 102 can be passed to therefrigerated dryer 106 and then direct to an end user.

The refrigerated dryer 106 includes an evaporator 110, refrigerantcompressor 112, and a condenser 114. The refrigerated dryer 106 can alsoinclude an expansion valve 116 and a hot gas bypass valve 118. Theexpansion valve 116 is used to rapidly expand (and thus cool)refrigerant and can be part of the evaporator in some embodiments, butnot all embodiments need include the expansion valve 116. Not allembodiments of the refrigerated dryer need include the hot gas bypassvalve 118.

The evaporator 110 can be any suitable device operable to absorb heatfrom a surrounding component/fluid, etc. As suggested above, theevaporator 110 can integrate the expansion valve 116 and in general isstructured as a heat exchanger to exchange heat between a cooledrefrigeration fluid and a passing flow stream (such as the wetcompressed air flow stream produced by operation of the compressor 102).Various constructions of the evaporator 110 are contemplated in whichrefrigeration fluid is in thermal communication with the wet compressedgas. For example, the evaporator 110 can include a surface that isdirectly contacted by the passing flow stream of wet compressed gas suchthat thermal energy is exchanged directly between the refrigerationfluid and the wet compressed gas. But in other forms the evaporator 110can be structured to include intermediate thermally conductive structurebetween the evaporator 110 and the wet compressed gas such that thermalenergy is exchanged via the intermediate structure. In either event, theevaporator 110 is used to elevate the temperature of the refrigerationfluid while cooling the temperature of the wet compressed gas.

The refrigerant compressor 112 is any suitable compressor that canelevate the pressure of refrigeration fluid for purposes of flowing thefluid through and participating in the refrigeration cycle. Any suitabletype of compressor is contemplated that is capable of producingsufficient pressure and flow rate of refrigeration fluid in the cycle.As used herein, and unless indicated to the contrary, use of the termcompressor is intended to cover all devices that serve to elevate thepressure of the refrigeration fluid and provide a motive force toencourage flow of the refrigeration fluid throughout the closed cycle ofthe refrigerated dryer

The condenser 114 is any suitable device capable of cooling therefrigeration fluid in the refrigerated dryer 106. In one non-limitingform the condenser 114 is an air cooled condenser in which local ambientair, or a flow stream of local ambient air, is used to exchange heatwith the high temperature refrigeration fluid flowing through thecondenser 114.

The compressor system 100 further includes a condensate harvester 120for collecting condensate produced as a consequence of operation of therefrigerated dryer 106, and providing that condensate to the condenser114 of the refrigerated dryer 106. The condensate harvester 120 includesa condensate collector 122 structured to direct liquid condensate awayfrom the evaporator 110, a condensate drain 124 and check valve 126 (notrequired in all embodiments), and an expansion tank 128 useful fordepositing and storage of condensate collected from operation of theevaporator 110.

The expansion tank 128 can take on a variety of forms. In onenon-limiting example, the expansion tank 128 can be a closed vesselhaving a venting/breather feature (to permit the vessel to breathe andaccept volumetric changes in liquid level with minimal disruptions ininternal gas pressurization. Such a breather/vent can take any varietyof forms well known and can include a filter to minimize intrusion offoreign debris into the expansion tank 128. In other embodiments thetank 128 can take on the form of an open top container.

The condensate harvester 120 also includes provisions to provide thecollected condensate to the condenser 114. A pump 134 and diffuser 136are in fluid communication with liquid from the expansion tank 128. Thepump 134 can be any device suitable to convey liquid from the expansiontank 128 to the condenser 114, such as a positive displacement pump,diaphragm pump, rotary pump, etc. The pump 134 can be a single speedpump in some embodiments in which case it can be cycled on and off asneeded, but in other forms can be a multi-speed pump. Such multi-speedpump can be a pump that operates at a variety of pump speeds, whethercontinuously variable or pre-set speeds.

The diffuser 136 is any suitable device either integrated with or influid communication with the pump 134 sufficient to disperse the liquidprovided from the pump 134 to the condenser 114. Such a diffuser 136 caninclude a spray head that disperses the passing liquid into separatestreams or droplets sufficient to provide some amount of cooling to thecondenser 114 to assist in heat rejection from the refrigerant in thecondenser 114.

In operation of the compressor system 100, when the wet compressed gasfrom the compressor 102 is provided to the evaporator 110, condensationcan be formed when the wet compressed gas is cooled below its dew point.Such condensation can take the form of water liquid when the gas to becompressed is a mixture of air and water vapor, to set forth just onenon-limiting example. The condensation can also take the form of solidwater in those instances where the temperature of the evaporator duringuse falls below a freezing point of the gas composition which is to beextracted from the compressed gas (e.g. water vapor in the case of airand water mixture). Condensation received by the collector 122 can beprovided to the expansion tank 128 where it can either accumulate overtime and/or be used to cool the condenser 114.

The compressor system 100 depicted in FIG. 1 includes a high condensatelevel sensor 130 which is used to detect a fluid level within theexpansion tank 128 that reaches a pre-determined high level mark. Insome embodiments the pre-determined high level mark is a maximumcapacity of the tank 128, or some other safety buffer located below amaximum capacity. In those embodiments in which the sensor 130 detectsliquid level at a location below a top of the expansion tank, thedistance can be offset to allow some amount of excess condensate tobuild-up, but still below a top level of the expansion tank.

A high liquid level in the tank 128 can therefore be at or below a toplevel of the tank 128. In those forms where the expansion tank 128 is aclosed vessel (possibly also including a vent/breather), the highcondensate level can occur at a level below a top of the closed vesselto prevent undesirable pressure buildup cessation of harvestingabilities, or an overflow condition. Overflow event includes an eventwhere condensate undesirably backflows into the conduit (such as conduitthat leads from the evaporator), or undesirably overflows from the topof an open container, or undesirably flows into an air vent of theexpansion tank 128, etc.

When the high condensate level sensor 130 detects a liquid level thatreaches the pre-determined level, a signal can be formed by operation ofthe sensor 130 and sent to an overflow valve 132 which is in fluidcommunication with the liquid in the tank 128. The valve 132 can take ona variety of forms, including electromechanical, hydraulic, pneumatic,etc. The valve 132 can include a mechanism, such as a solenoid, that ismoved between an open and a closed position. The solenoid can be biasedin one direction and energized to move in the other direction, to eitheropen or close the valve 132.

Upon receipt of a signal the overflow valve 132 can be opened to releaseliquid from the tank 128. The overflow valve can be in fluidcommunication with a fluid level in the tank that corresponds to thehigh liquid level, but can also be located at different heights as well.

The compressor system 100 depicted in FIG. 1 can also include a lowcondensate level sensor 142 which is used to detect a fluid level withinthe expansion tank 128 in which a predetermined insufficient level ofliquid is present. In some embodiments the pre-determined low level markis a minimum capacity of the tank 128 to provide liquid to the pump fora set period of time, or some other safety buffer located below aminimum capacity. In those embodiments in which the sensor 130 detectsliquid level at a location above a bottom of the expansion tank, thedistance can be offset to allow some amount of condensate to be providedto the pump to permit some time to shut down the pump, but still below abottom level of the expansion tank.

When the low condensate level sensor 142 detects a liquid level thatreaches the pre-determined level, a signal can be formed by operation ofthe sensor 142 and sent to the pump 134. Upon receipt of a signal thepump 134 can be switched off or shut down. The pump 134 can be in fluidcommunication with a fluid level in the tank that corresponds to the lowliquid level, but can also be located at different heights as well andin some embodiments located below a bottom of the tank 128.

The overflow valve 132 and/or the pump 134 can thus be controlledthrough detection of a high liquid level made possible by the highcondensate level sensor 130 and a low liquid level made possible by thelow condensate level sensor 142, respectively. Such a controller (eitherfor the valve 132 or pump 134, or both) can be a direct electricalcontrolled connection that switches the overflow valve 132 to an opencondition (or cuts power to the pump 134), or can be through anintermediate system such as an integrated circuit controller. Thus, thecontroller can be a programmable IC, but can also include analogcomponents such that a control action is realized. The controller caninclude any combination of electronic circuitry and components such asresistors, capacitors, and semiconductor devices, among potentialothers, A “controller” in this sense is any type of electrical devicesufficient to activate the system to release condensate from theexpansion tank. For example and as suggested above, the “controller” canbe a simple switch, a more complicated electrical circuit, or aprogrammable integrated circuit, among potential others, that activatesthe pump upon receipt of a voltage or current signal from the sensors,among potential others. As such, use of the term “controller” is notintended to apply exclusively to programmable IC type devices unlessotherwise indicated to the contrary. It is rather intended to encompassdevices/arrangements/configurations/etc that are useful to “control” thelevel of condensate through action of a pump, valve, etc. Furthermore,the controller can be one or many separate components that together workto provide operation of the system including opening and closing valves,regulating action of the pump, etc. The control can either be analog ordigital, and in this sense any signals developed from the highcondensate level sensor 130 or low condensate level sensor 142 can besampled at set periods or can be continuously monitored.

When the valve 132 is opened by detection of a high liquid level in thetank 128, the valve 132 can stay open for any duration or eventsufficient to indicate relief of water from the tank 128. For example,the valve can remain open for a pre-determined period of time such asthrough a digital timer regardless of whether the high condensate levelsensor 130 continues to detect a high liquid level. In other forms thevalve 132 can be opened for a period of time that is calculated to draina set quantity of liquid assuming certain flow behaviors of valve type,fluid type, fluid pressures and temperature, etc.

Turning now to FIG. 2, where like reference numerals refer to likeelements described elsewhere in the application, the expansion tank 128is further connected in fluid communication with a utility water supply138 which can be used to supplement liquid within the tank 128 harvestedfrom condensate developed by the evaporator 110. A valve 140 can be usedto open and close a conduit that provides water from the utility watersupply 138.

The utility water source 138 can be a large network of pipes serviced bya water provider that pulls water from any variety of sources such asreservoirs, water towers, tanks, etc. A utility provider of water, muchlike an electric utility, is one example of a utility water source. Thenetwork is generally a series of interconnected conduits that arecapable of servicing a wide variety of end customers, some of which canuse their own filtration and intermediate tanks, reservoirs, but all ofwhich generally remain connected through valving and other devices tothe utility water source.

The condensate provided to the tank 128 formed by operation of theevaporator 110 can be condensate from whatever vapor is entrained in thecompressed gas of choice (e.g. water vapor, but other vapors alsopossible). When utility water is supplied to the tank 128, the liquidprovided to the pump 134 can be either the water from the utility watersupply, liquid from the vapor that was condensed by the evaporator, or amixture of the two depending upon the particular application.

The valve 140 can be controlled by detection of low liquid level throughlow condensate level sensor 142 to permit entry of water from theutility water supply 138 to enter the tank 128. The valve 140 can remainopen for a set period of time such as could be implemented using atimer. A pre-determined period of time that the valve 140 is opened canbe determined through water supply pressure and valve geometries, amongother possibilities. Persons of skill in the art can determinequantities of fluid delivered through a valve using knowledge ofupstream fluid flow properties such as pressure. The time can bedetermined from assumptions of pressure and a desired quantity to fillthe expansion tank. Alternatively, persons of skill in the art can picka set period of time without regard to any information pertaining towater supply pressure, valve configuration, etc. In still other forms,the valve 140 could remain open until water reaches the overflow sensor128.

The valve 140 can take on a variety of forms, includingelectromechanical, hydraulic, pneumatic, etc. The valve 140 can includea mechanism, such as a solenoid, that is moved between an open and aclosed position. The solenoid can be biased in one direction andenergized to move in the other direction, to either open or close thevalve 140.

Turning now to FIG. 3, where like reference numerals refer to likeelements described elsewhere in the application, water from the utilitywater supply 138 can be mixed with, or replace, liquid from theexpansion tank 128 through action of a valve 142. The valve 142 can beany suitable device for controlling the passage of fluid through a pipeor duct, such as a device that permits fluid flow in one direction only,a device that can select between sources, and a device that can mixstreams together. The valving member can be an actuatable valve (such asan electric, pneumatic, or hydraulically driven valve) or a passivevalving device such as a venture that acts to entrain one source offluid with another. Some examples of different types: the valve 142 canbe a mixing valve, 3-way valve, a 3-way thermal mixing valve, or aVenturi-type valve, among potential others.

A 3-way thermal mixing valve can be used to ensure constant temperatureof fluid provided to the condenser 114. The thermal nature of the valvecan help ensure or seek to achieve more or less consistent temperaturein light of the fact that condensate collected from the evaporator 110is usually at lower temperature than water from the utility water supply138.

In another example, in case the valve 142 is of a Venturi type, thevalve 142 can be a passive device that entrains, via suction action,liquid from the tank 128 using a flow of utility water. The valve 142can include internal passages that accelerate a flow of utility waterwhich is used a primary flow stream to encourage entrainment of arelatively low speed and higher pressure liquid from the tank 128.

The liquid in the tank 128 can be in communication with the valve 142using any number of conduits and devices. In one form a conduit can beprovided that has an opening at the bottom of the tank and a check valvedisposed along the conduit between the bottom of the tank and the valve142. The check valve can be used to discourage a flow of water from thevalve 142 to the tank 128, and instead to permit a flow of liquid fromthe tank 128 to the valve 142 when sufficient suction pressure urges thecheck valve to open to permit entrainment of the liquid from the tank128. A check valve can also be added to the line from the utility watersupply 138 to discourage a flow of water from the valve 142 to thesupply 138, and instead to permit a flow of liquid from the supply 138to the valve 142 when sufficient suction pressure exists on the valve142 side of the check valve (in addition to water pressure on theutility water supply side) urges the check valve to open to permit flowof water from the utility water supply 138.

In other embodiments, the high condensate level sensor 130 and overflowvalve 130 combination can be used as indicator when to switch a 3-wayvalve 142 to use harvested condensate. Such an embodiment can includeopening the valve 132 for a period of time less than a period of timerequired to completely drain the tank 128, with the residual liquid inthe tank used by the pump 134 via the valve 142 for anotherpre-determined period of time.

In still other forms, the valve 142 in the form of a three way valvecould be actuated by an embodiment of the tank 128 that includes a lowcondensate level sensor 130.

In still further forms, the valve 140 can be opened as soon as thecompressor system 100 is activated, thus supplying water to thecondenser 114 continuously and entraining condensate whenever it iscollected in the tank 128.

Turning now to FIG. 4, another embodiment of the compressor system 100includes the ability to regulate the rate of liquid delivery by the pump134 to the condenser 114 depending on a temperature related to operationof the condenser 114. The compressor system 100 can include atemperature sensor 144 structured to detect a temperature related tooperation of the condenser 114. At a pre-determined temperature, thetemperature sensor 144 can provide a signal useful in switching the pump134 on to provide water to the condenser 114. In this sense the pump 134can be controlled (used in the sense of ‘controlling’ as described abovein the other embodiments) based upon temperature. The pump 134 can beregulated in speed and state (e.g. on v. off), to set forth just a fewexamples. In one form the temperature related to operation of thecondenser 114 can be an outlet flow temperature of refrigerant from thecondenser, such as that shown in the illustrated embodiment. Otherlocations are also contemplated. The embodiment described in FIG. 4 canbe used under variable load conditions. In one form the embodiment canprovide consistent condenser temperatures under variable loadconditions.

Unless indicated to the contrary, like reference numerals refer to likeelements between the different embodiments. For example, compressor 102and its variations discussed above with respect to any given embodimentapply across all embodiments of the compressor 102. Thus, variations ofthe compressor 102 mentioned in FIG. 1 also apply to the embodiments ofFIG. 2, and vice versa. No limitation is intended to limit variations ofthe compressor 102 mentioned above with respect to FIG. 1 to only applyto the embodiments of the compressor system 100 discussed with respectto FIG. 1, unless explicitly indicated to the contrary. The same appliesto any other reference numeral/element pairing found throughout theinstant application.

One aspect of the present application includes an apparatus comprising agas compressor system operable to produce a wet compressed gas andhaving a compressor outlet in fluid communication with a refrigerateddryer, the refrigerated dryer including a condenser for cooling arefrigeration fluid and a heat exchanger that exchanges heat from thewet compressed gas with a refrigeration fluid of the refrigerated dryerto cool and remove moisture from the wet compressed gas while heatingthe refrigeration fluid, the gas compressor system also including: anexpansion tank structured to contain water, the expansion tank orientedto receive a condensate produced from the heat exchanger as it removesmoisture from the wet compressed gas, a temperature sensor configured tosense temperature of a refrigeration fluid flowing from a condenser ofthe refrigerated dryer to the heat exchanger, and a pump in fluidcommunication with the expansion tank and configured to deliver waterfrom the expansion tank to the condenser, the pump regulated by the gascompressor system when the temperature sensor detects a temperature ofthe refrigeration fluid at or above a predetermined temperature.

A feature of the present application provides wherein regulation of thepump includes operating the pump at different speeds to provide variableflow rate of water from the expansion tank to the condenser of therefrigerated dryer.

Another feature of the present application provides wherein theexpansion tank further includes a low water level sensor.

Still another feature of the present application provides wherein thecompressor system is structured to trigger a valve disposed between theexpansion tank and a utility water supplier, the valve configured topermit introduction of water into the expansion tank from a continuoussupply of water from a utility water supplier in the event that the lowwater level sensor detects a low water level.

Yet another feature of the present application provides wherein thevalve is held open for a period of time in which a water level riseswithin the tank to a level below a pre-determined water level.

Still yet another feature of the present application provides whereinthe expansion tank further includes a high water level sensor.

Yet still another feature of the present application provides whereinthe valve is held open until the water level rises within the tank tothe high water level sensor.

A further feature of the present application provides further includesan overflow valve structured to release water from the expansion tankwhen the water level reaches a pre-determined overflow condition.

Another aspect of the present application provides an apparatuscomprising a compressor system including gas compressor structured toproduce a flow of wet compressed gas and a refrigerated dryer having aclosed refrigeration cycle, wherein the closed refrigeration cycleincludes: a compressor for pressurizing a refrigeration fluid andconveying the refrigeration fluid throughout the closed refrigerationcycle, a condenser for cooling the refrigeration fluid after it has beencompressed by the compressor, and an evaporator for receiving therefrigeration fluid from the condenser and exchanging heat with a wetcompressed gas flow stream produced by the gas compressor, wherein thecompressor system also includes: an expansion tank configured to receivecondensate produced from the evaporator, the condensate extracted fromthe wet compressed gas flow stream when it has been cooled by action ofthe evaporator, a pump in fluid communication with the expansion tankand configured to provide water from the expansion tank to thecondenser, and a temperature sensor configured to sense temperature ofthe refrigeration fluid on an outlet side of the condenser, and whereinthe compressor system triggers the pump to provide water from theexpansion tank to the condenser when a temperature signal provided bythe temperature sensor exceeds a threshold indicating an elevatedtemperature in the refrigeration fluid on the outlet side of thecondenser.

A feature of the present application provides wherein the expansion tankis coupled with a conduit structured to flow water from a utility watersource that supplies a continuous flow of water.

Another feature of the present application provides wherein theexpansion tank includes a low water level sensor and the conduitincludes a valve structured to open and close the conduit.

Still another feature of the present application provides wherein thevalve is commanded by the compressor system to open and flow water tothe expansion tank when the low water level sensor indicates a low waterlevel in the expansion tank.

Yet another feature of the present application provides wherein theexpansion tank includes a high water level sensor, and wherein anoverflow valve is coupled with the expansion tank to vent excess waterwhen the high water level detects water.

Still yet another feature of the present application provides whereinthe compressor system is structured to command the pump to flow waterfor a time period shorter than a period required to overflow theexpansion tank.

Yet still another feature of the present application provides whereinthe compressor system controls the pump between a number ofpre-determined pump speeds.

Yet another aspect of the present application provides a methodcomprising compressing a gas containing water vapor to form a wetcompressed gas, flowing the wet compressed gas through an evaporatorheat exchanger to extract water condensate from the wet compressed gas;the evaporator heat exchanger part of a refrigerated air dryer,harvesting the water condensate in an expansion tank, and variablyregulating a pump to provide a demand-based flow rate of water from theexpansion tank to a condenser of the refrigerated dryer based upon atemperature of refrigeration fluid of the condenser, the demand-basedflow rate of water a function of the temperature of the refrigerationfluid of the condenser.

A feature of the present application further includes sensing a lowwater level in the expansion tank.

Another feature of the present application further includes flowingwater from a continuous source of utility water in response to thesensing a low water level.

Still another feature of the present application further includesclosing a valve to stop the flowing of water from the continuous sourceof utility water, and which further includes a high water level sensor.

Yet another feature of the present application further includes anoverflow valve configured to vent water from the expansion tank when itreceives a signal indicative of a high water level sensed by the highwater level sensor.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinventions are desired to be protected. It should be understood thatwhile the use of words such as preferable, preferably, preferred or morepreferred utilized in the description above indicate that the feature sodescribed may be more desirable, it nonetheless may not be necessary andembodiments lacking the same may be contemplated as within the scope ofthe invention, the scope being defined by the claims that follow. Inreading the claims, it is intended that when words such as “a,” “an,”“at least one,” or “at least one portion” are used there is no intentionto limit the claim to only one item unless specifically stated to thecontrary in the claim. When the language “at least a portion” and/or “aportion” is used the item can include a portion and/or the entire itemunless specifically stated to the contrary. Unless specified or limitedotherwise, the terms “mounted,” “connected,” “supported,” and “coupled”and variations thereof are used broadly and encompass both direct andindirect mountings, connections, supports, and couplings. Further,“connected” and “coupled” are not restricted to physical or mechanicalconnections or couplings.

What is claimed is:
 1. An apparatus comprising: a gas compressor systemoperable to produce a wet compressed gas and having a compressor outletin fluid communication with a refrigerated dryer, the refrigerated dryerincluding a condenser for cooling a refrigeration fluid and a heatexchanger that exchanges heat from the wet compressed gas with arefrigeration fluid of the refrigerated dryer to cool and removemoisture from the wet compressed gas while heating the refrigerationfluid, the gas compressor system also including: an expansion tankstructured to contain water, the expansion tank oriented to receive acondensate produced from the heat exchanger as it removes moisture fromthe wet compressed gas; a temperature sensor configured to sensetemperature of a refrigeration fluid flowing from a condenser of therefrigerated dryer to the heat exchanger; and a pump in fluidcommunication with the expansion tank and configured to deliver waterfrom the expansion tank to the condenser, the pump regulated by the gascompressor system when the temperature sensor detects a temperature ofthe refrigeration fluid at or above a predetermined temperature.
 2. Theapparatus of claim 1, wherein regulation of the pump includes operatingthe pump at different speeds to provide variable flow rate of water fromthe expansion tank to the condenser of the refrigerated dryer.
 3. Theapparatus of claim 2, wherein the expansion tank further includes a lowwater level sensor.
 4. The apparatus of claim 3, wherein the compressorsystem is structured to trigger a valve disposed between the expansiontank and a utility water supplier, the valve configured to permitintroduction of water into the expansion tank from a continuous supplyof water from a utility water supplier in the event that the low waterlevel sensor detects a low water level.
 5. The apparatus of claim 4,wherein the valve is held open for a period of time in which a waterlevel rises within the tank to a level below a pre-determined waterlevel.
 6. The apparatus of claim 4, wherein the expansion tank furtherincludes a high water level sensor.
 7. The apparatus of claim 6, whereinthe valve is held open until the water level rises within the tank tothe high water level sensor.
 8. The apparatus of claim 4, and whichfurther includes an overflow valve structured to release water from theexpansion tank when the water level reaches a pre-determined overflowcondition.
 9. An apparatus comprising: a compressor system including gascompressor structured to produce a flow of wet compressed gas and arefrigerated dryer having a closed refrigeration cycle, wherein theclosed refrigeration cycle includes: a compressor for pressurizing arefrigeration fluid and conveying the refrigeration fluid throughout theclosed refrigeration cycle; a condenser for cooling the refrigerationfluid after has been compressed by the compressor; and an evaporator forreceiving the refrigeration fluid from the condenser and exchanging heatwith a wet compressed gas flow stream produced by the gas compressor;wherein the compressor system also includes: an expansion tankconfigured to receive condensate produced from the evaporator, thecondensate extracted from the wet compressed gas flow stream when it hasbeen cooled by action of the evaporator; a pump in fluid communicationwith the expansion tank and configured to provide water from theexpansion tank to the condenser; and a temperature sensor configured tosense temperature of the refrigeration fluid on an outlet side of thecondenser; and wherein the compressor system triggers the pump toprovide water from the expansion tank to the condenser when atemperature signal provided by the temperature sensor exceeds athreshold indicating an elevated temperature in the refrigeration fluidon the outlet side of the condenser.
 10. The apparatus of claim 9,wherein the expansion tank is coupled with a conduit structured to flowwater from a utility water source that supplies a continuous flow ofwater.
 11. The apparatus of claim 10, wherein the expansion tankincludes a low water level sensor and the conduit includes a valvestructured to open and close the conduit.
 12. The apparatus of claim 11,wherein the valve is commanded by the compressor system to open and flowwater to the expansion tank when the low water level sensor indicates alow water level in the expansion tank.
 13. The apparatus of claim 12,wherein the expansion tank includes a high water level sensor, andwherein an overflow valve is coupled with the expansion tank to ventexcess water when the high water level detects water.
 14. The apparatusof claim 13, wherein the compressor system is structured to command thepump to flow water for a time period shorter than a period required tooverflow the expansion tank.
 15. The apparatus of claim 14, wherein thecompressor system controls the pump between a number of pre-determinedpump speeds.
 16. A method comprising: compressing a gas containing watervapor to form a wet compressed gas; flowing the wet compressed gasthrough an evaporator heat exchanger to extract water condensate fromthe wet compressed gas, the evaporator heat exchanger part of arefrigerated air dryer; harvesting the water condensate in an expansiontank; and variably regulating a pump to provide a demand-based flow rateof water from the expansion tank to a condenser of the refrigerateddryer based upon a temperature of refrigeration fluid of the condenser,the demand-based flow rate of water a function of the temperature of therefrigeration fluid of the condenser.
 17. The method of claim 16, whichfurther includes sensing a low water level in the expansion tank. 18.The method of claim 17, which further includes flowing water from acontinuous source of utility water in response to the sensing a lowwater level.
 19. The method of claim 18, which further includes closinga valve to stop the flowing of water from the continuous source ofutility water, and which further includes a high water level sensor. 20.The method of claim 19, which further includes an overflow valveconfigured to vent water from the expansion tank when it receives asignal indicative of a high water level sensed by the high water levelsensor.